1. Field of the Invention
The present invention relates to a duplex printing apparatus and duplex printing method that print pluralities of images on both surfaces of a continuous sheet.
2. Description of the Related Art
There has been provided a printing apparatus that sequentially prints a plurality of images on a continuous sheet, and cuts the sheet on an image (page) basis. In such a printing apparatus, a conveyance state of the continuous sheet is influenced by an individual difference of the printing apparatus, the type or width of the sheet, use environment, or the like, and therefore a conveyance distance of the continuous sheet per unit time includes a certain level of error For this reason, in order to prevent the continuous sheet from being cut in the middle of an image, a method that, between images, provides a non-image area printed with a cut mark indicating a cutting position, and on the basis of timing when a detector detects the cut mark, cuts the continuous sheet with a cutter is used.
However, in the case where in order to detect such a cut mark, the detector performs a reading operation throughout the continuous sheet, a pattern in an image, which is similar to the cut mark, may also be determined as the cut mark to cut the continuous sheet in the middle of the image.
To address such a problem, Japanese Patent Laid-Open No. 2012-158122 discloses a method that performs a reading operation by a detector only on the vicinity of a non-image area, which is printed with a cut mark. Also, Japanese Patent Laid-Open No. 2012-158122 discloses a configuration in which by focusing on the fact that an error in conveyance amount of a continuous sheet is increased along with an increase in conveyance distance of the continuous sheet, i.e., an increase in size of an image, a size of a non-image area between two successive images and a reading area by the detector are adjusted depending on a size of a precedent image. According to such Japanese Patent Laid-Open No. 2012-158122, in a non-image area having a size enough to include a conveyance error of the continuous sheet, a cut mark can be detected, and therefore even in the case where a conveyance error occurs, the continuous sheet can be cut in a correct position.